The longitudinal association between depressive symptoms and initiation of insulin therapy in people with type 2 diabetes in primary care.

Nefs G, Pop VJ, Denollet J, Pouwer F - PLoS ONE (2013)

Bottom Line:
After a mean follow-up of 1,597 ± 537 days, 253 (18%) participants had started insulin therapy.The rate of insulin initiation did not differ between depressed and non-depressed participants.The association remained non-significant when individual candidate confounders were added to the age- and sex-adjusted base model.

Affiliation: CORPS - Center of Research on Psychology in Somatic diseases, Department of Medical and Clinical Psychology, Tilburg University, Tilburg, The Netherlands.

ABSTRACT

Objective: To examine whether depressive symptoms are associated with time to insulin initiation in insulin-naïve people with type 2 diabetes in primary care.

Methods: 1,389 participants completed the Edinburgh Depression Scale (EDS) in 2005 and were followed until: 1) insulin therapy was started, 2) death, 3) an oral antihyperglycemic drug (OAD) prescription gap >1 year, 4) last OAD prescription in 2010 or 5) the end of the study (December 31, 2010). Cox regression analyses were used to determine whether there was a difference in time to insulin initiation between people with a low versus a high depression score at baseline, adjusting for potential demographic and clinical confounders, including HbA1c levels.

Results: The prevalence of depression (EDS ≥ 12) was 12% (n=168). After a mean follow-up of 1,597 ± 537 days, 253 (18%) participants had started insulin therapy. The rate of insulin initiation did not differ between depressed and non-depressed participants. People with depression were not more likely to start insulin therapy earlier or later than their non-depressed counterparts (HR=0.98, 95% CI 0.66-1.45), also after adjustment for sex and age (HR=0.95, 0.64-1.42). The association remained non-significant when individual candidate confounders were added to the age- and sex-adjusted base model.

Conclusions: In the present study, depression was not associated with time to insulin initiation. The hypothesis that depression is associated with delayed initiation of insulin therapy merits more thorough testing, preferably in studies where more information is available about patient-, provider- and health care system factors that may influence the decision to initiate insulin.

Mentions:
During a mean follow-up period of 1,597±537 days (range 17–1,964), 253 (18%) participants added insulin to their treatment regimen. The rate of insulin initiation did not differ between people with and without high depressive symptoms (17%, n = 28 vs. 18%, n = 225; p = 0.58). When examining the Kaplan-Meier curves, we also did not observe a difference in time to insulin initiation for both groups (log-rank test X2[1] = 0.01, p = 0.92), with a mean time to event of 1,783 (95% CI 1,758–1,807) and 1,749 (95% CI 1,671–1,828) days for those without and with depression, respectively (Figure 1). As only 18% of the total sample switched to insulin therapy in the follow-up period, median survival times could not be reported. In univariable Cox regression analysis (n = 1,387; two cases censored before the earliest event in stratum), we found a non-significant HR of insulin initiation (0.98, 95% CI 0.66–1.45, p = 0.92).

Mentions:
During a mean follow-up period of 1,597±537 days (range 17–1,964), 253 (18%) participants added insulin to their treatment regimen. The rate of insulin initiation did not differ between people with and without high depressive symptoms (17%, n = 28 vs. 18%, n = 225; p = 0.58). When examining the Kaplan-Meier curves, we also did not observe a difference in time to insulin initiation for both groups (log-rank test X2[1] = 0.01, p = 0.92), with a mean time to event of 1,783 (95% CI 1,758–1,807) and 1,749 (95% CI 1,671–1,828) days for those without and with depression, respectively (Figure 1). As only 18% of the total sample switched to insulin therapy in the follow-up period, median survival times could not be reported. In univariable Cox regression analysis (n = 1,387; two cases censored before the earliest event in stratum), we found a non-significant HR of insulin initiation (0.98, 95% CI 0.66–1.45, p = 0.92).

Bottom Line:
After a mean follow-up of 1,597 ± 537 days, 253 (18%) participants had started insulin therapy.The rate of insulin initiation did not differ between depressed and non-depressed participants.The association remained non-significant when individual candidate confounders were added to the age- and sex-adjusted base model.

Affiliation:
CORPS - Center of Research on Psychology in Somatic diseases, Department of Medical and Clinical Psychology, Tilburg University, Tilburg, The Netherlands.

ABSTRACT

Objective: To examine whether depressive symptoms are associated with time to insulin initiation in insulin-naïve people with type 2 diabetes in primary care.

Methods: 1,389 participants completed the Edinburgh Depression Scale (EDS) in 2005 and were followed until: 1) insulin therapy was started, 2) death, 3) an oral antihyperglycemic drug (OAD) prescription gap >1 year, 4) last OAD prescription in 2010 or 5) the end of the study (December 31, 2010). Cox regression analyses were used to determine whether there was a difference in time to insulin initiation between people with a low versus a high depression score at baseline, adjusting for potential demographic and clinical confounders, including HbA1c levels.

Results: The prevalence of depression (EDS ≥ 12) was 12% (n=168). After a mean follow-up of 1,597 ± 537 days, 253 (18%) participants had started insulin therapy. The rate of insulin initiation did not differ between depressed and non-depressed participants. People with depression were not more likely to start insulin therapy earlier or later than their non-depressed counterparts (HR=0.98, 95% CI 0.66-1.45), also after adjustment for sex and age (HR=0.95, 0.64-1.42). The association remained non-significant when individual candidate confounders were added to the age- and sex-adjusted base model.

Conclusions: In the present study, depression was not associated with time to insulin initiation. The hypothesis that depression is associated with delayed initiation of insulin therapy merits more thorough testing, preferably in studies where more information is available about patient-, provider- and health care system factors that may influence the decision to initiate insulin.